Radiographic method and apparatus for detection of cracks, defects, or leak pathways in materials and assemblies

ABSTRACT

Example systems and methods for testing materials and assemblies for voids, cracks, or other defects are provided. One example system for testing a part includes a chamber configured to accept the part, and a vacuum source connected to the chamber. The example system also includes a fluid source connected to the chamber and configured to provide a radioactive or isotope-labeled fluid to the chamber. In addition, the example system includes a detector configured to detect a presence or absence of radioactivity or the isotope-labeled fluid in the part.

CROSS REFERENCE TO RELATED APPLICATION

The present disclosure is a continuation of U.S. patent application Ser.No. 15/062,166, filed on Mar. 6, 2016, the entire contents of which areherein incorporated by reference.

FIELD

The present disclosure relates generally to radiographic systems andmethods for inspecting materials and assemblies, and more particularly,to radiographic systems and methods for detecting voids, cracks, orother defects in materials and assemblies.

BACKGROUND

Proof testing is a nondestructive testing technique for verifying that apart, component, or assembly is suitable to withstand the conditions inwhich the part, component, or assembly was designed to operate. By wayof example, proof testing may involve subjecting a part to twice thepart's maximum design load and observing whether the part is damaged inany way. Manufacturers in many industries use proof testing as way toscreen a part for manufacturing anomalies before the part is allowed topass “inspection” and enter service. Similarly, proof testing may alsobe used to verify that an old part is still functioning properly and isfit for additional service.

In some examples, a part may “pass” proof testing but neverthelessinclude one or more latent defects. For instance, the proof test mightnot detect an inconsistency that could cause the part to not be able tosustain a particular design load. Such latent defects may take the formof internal voids, cracks, or other defects that might not be observablefrom viewing the part's surface. Further, a latent defect might not bedetectable using x-ray or ultrasound inspection either. For example, dueto the geometry or variable density of the part, x-ray inspection mightnot be able to detect or reveal a crack in the part. Additionally, x-rayinspection might not be able to detect a crack that is orientedorthogonal to an x-ray detector array. As another example,geometric/material inhomogeneity or latent defects may create additionalechoes or shadows, making ultrasound or x-ray data expensive to analyzeand making detection of inconsistencies/defects difficult.

SUMMARY

In one example, a method for testing a part is provided. The methodincludes exposing the part to a radioactive or isotope-labeled fluidunder pressure, and, after exposing the part to the radioactive orisotope-labeled fluid under pressure, detecting a presence or absence ofradioactivity or the isotope-labeled fluid entrained in the part.

In another example, a system for testing a part is provided. The systemcomprises a chamber configured to accept the part. The system furthercomprises a vacuum source connected to the chamber. The system alsocomprises a fluid source connected to the chamber and configured toprovide a radioactive or isotope-labeled fluid to the chamber.Additionally, the system comprises a detector configured to detect apresence or absence of radioactivity or the isotope-labeled fluid in thepart.

In still another example, a controller is provided. The controllercomprises a processor and a computer-readable medium having storedtherein instructions that are executable to cause the controller toperform functions. The functions include causing a vacuum source toreduce a pressure in a chamber, with a part located in the chamber. Thefunctions also include causing a fluid source connected to the chamberto provide a radioactive or isotope-labeled fluid to the chamber. Thefunctions further include causing a fluid reclamation container toremove the radioactive or isotope-labeled fluid from the chamber. Andthe functions include causing a detector to detect a presence or absenceof radioactivity or the isotope-labeled fluid in the part.

The features, functions, and advantages that have been discussed can beachieved independently in various examples or may be combined in yetother examples further details of which can be seen with reference tothe following description and figures.

BRIEF DESCRIPTION OF THE FIGURES

The novel features believed characteristic of the illustrative examplesare set forth in the appended claims. The illustrative examples,however, as well as a preferred mode of use, further objectives anddescriptions thereof, will best be understood by reference to thefollowing detailed description of an illustrative example of the presentdisclosure when read in conjunction with the accompanying figures,wherein:

FIG. 1 is a schematic diagram of an example system according to thedisclosure.

FIG. 2 is a schematic diagram of an example controller according to thedisclosure.

FIG. 3 is a flowchart of an example method for testing a part accordingto the disclosure.

FIG. 4 is a flowchart of another example method for testing a partaccording to the disclosure.

DETAILED DESCRIPTION

Disclosed examples will now be described more fully hereinafter withreference to the accompanying figures, in which some, but not all of thedisclosed examples are shown. Indeed, several different examples may beprovided and should not be construed as limited to the examples setforth herein. Rather, these examples are provided so that thisdisclosure will be thorough and complete and will fully convey the scopeof the disclosure to those skilled in the art.

Within examples, radiographic systems and methods for inspectingmaterials and assemblies are provided. For instance, the systems andmethods may facilitate detecting voids, cracks, or other defects inmaterials and assemblies. As described herein, the systems and methodsleverage the ability of a radioactive or isotope-labeled fluid topermeate through a material or assembly in order to detect the presenceor absence of internal defects in the material or assembly. The systemsand methods described herein may facilitate detecting defects, such ascracks or voids in parts with complex shape geometries or multipledensity/inhomogeneous constituents.

Advantageously, the systems and methods may detect the presence orabsence of internal defects without applying loads or pressure (beyondthe design loads) on the materials or assemblies. The systems andmethods provide an alternative to proof testing. Further, the systemsand methods may also facilitate detecting internal cracks or voids thatmight not otherwise be detectable using other or cost-effectivedetection techniques. For example, the systems and methods mayfacilitate detecting latent defects in a part that might not be visiblewith x-ray inspection due to the orientation of the defect with respectto the detector array or the size and shape of the defect. As anotherexample, the systems and methods may facilitate detecting latent defectsin a part that might not be observable with ultrasonic inspection due tothe inability of a part to withstand exposure to ultrasound techniquesor due to uninterpretable ultrasonic echoes or shadows caused by thegeometry or material(s) of the part.

In accordance with examples disclosed herein, an example system includesa chamber, a vacuum source, a fluid source, and a detector. The chambermay be configured to accept a part. For example, the chamber may be anautoclave. The vacuum source may be connected to the chamber and may beconfigured to remove gas molecules from the chamber and create a partialvacuum in the chamber. The fluid source may also be connected to thechamber and configured to provide a radioactive or isotope-labeled fluidto the chamber. By way of example, after creating a partial vacuum inthe chamber and while the part is in the chamber, the fluid source mayprovide the radioactive or isotope-labeled fluid to the chamber.

Within the chamber, the radioactive or isotope-labeled fluid may thenpermeate through the part. For instance, the part may have a permeablesurface or the part may be a polymeric composite or polymeric part,thereby being permeable to the radioactive or isotope-labeled fluid,which can permeate through the part. If the part includes any internalcracks or voids, the radioactive or isotope-labeled fluid may thenpermeate into the cracks or voids and become entrained or trapped withinthe defects. The presence of the entrained fluid may then detectable byan x-ray detector, for instance.

The detector may then be used to detect a presence or absence ofradioactivity or the isotope-labeled fluid in the part. By way ofexample, if the part was exposed to a radioactive fluid, the detectormay be configured to detect the presence or absence of radioactivityentrained in the part. On the other hand, if the part was exposed to anisotope-labeled fluid, the detector may be configured to detect thepresence or absence of the isotope-labeled fluid entrained in the part.In one example, the detector may be connected to the chamber andconfigured to detect the presence or absence of radioactivity or theisotope-labeled fluid after removal of the radioactive orisotope-labeled fluid from the chamber. Alternatively, the detector maybe separate from the chamber and the part may be removed from thechamber to a location of the detector. In one example, the detector maybe an x-ray detector.

If the detector detects the presence of radioactivity or theisotope-labeled fluid (e.g., more than a threshold detectable amount ofradioactivity or more than a threshold amount of isotope-labeled fluid),the presence of the radioactivity or the isotope-labeled fluid may beinterpreted to mean that the part potentially contains a latent defect.For example, the detector may detect radioactivity or isotope-labeledfluid entrained within the part or emanating from a void or crack withinthe part. On the other hand, if the detector detects an absence ofradioactivity or absence of the isotope-labeled fluid (e.g., less than athreshold concentration), the absence of the radioactivity orisotope-labeled fluid may be interpreted to mean that the part does notinclude any significant latent defects.

Various other features of the example system discussed above, as well asmethods for testing a part using these systems, are also describedhereinafter with reference to the accompanying figures.

Referring to the figures, FIG. 1 is a schematic diagram of an examplesystem 100. In line with the discussion above, the example system 100may be used to test a part. As shown in FIG. 1, the example system 100includes a chamber 102, a vacuum source 104, a fluid source 106, a fluidreclamation container 108, a detector 110, a controller 112, and anindicator 114.

As shown in FIG. 1, the controller 112 may be coupled to the vacuumsource 104, fluid source 106, fluid reclamation container 108, detector110, and indicator 114 via one or more wired or wireless links, systembuses, networks, or other connection mechanisms 116. In addition, eachof the vacuum source 104, fluid source 106, and fluid reclamationcontainer 108 may be coupled to the chamber via fluid pathways 118, 120,122. Further, the fluid source 106 may be coupled to the fluidreclamation container 108 via a fluid pathway 124.

The chamber 102 may be configured to accept a part. In one example, thechamber 102 may be an autoclave. More generally, the chamber 102 may beany cavity or space that may enclose a part and be sealed for a periodof time. For example, the chamber 102 may have a pressure-tight lid ordoor that may be opened to insert a part and closed to facilitateexposing the part to a radioactive or isotope-labeled fluid underpressure.

The vacuum source 104 may be connected to the chamber 102 and configuredto regulate the pressure in the chamber 102. In particular, the vacuumsource 104 may be configured to create a partial vacuum in the chamber102 by removing gas molecules from the chamber 102. By way of example,the vacuum source 104 may be a vacuum pump. In an example in which thechamber 102 is an autoclave, the vacuum source 104 may be an integratedcomponent of the autoclave.

The fluid source 106 may be configured to provide a radioactive orisotope-labeled fluid to the chamber 102. In one example, the fluidsource 106 may store the radioactive or isotope-labeled fluid andinclude a valve for releasing the radioactive or isotope-labeled fluidinto the chamber 102 via the fluid pathway 120. The radioactive orisotope-labeled fluid may take any of a variety of forms, depending onthe desired configuration. The fluid source 106 may provide aradioactive gas, such as radon, radioactive helium, or radioactivexenon. Alternatively, the fluid source 106 may provide a radioactiveliquid. The isotope-labeled fluid may be radioactive or non-radioactive.Further the isotope-labeled fluid may be a liquid (e.g., deuteratedwater) or a gas (e.g., deuterated methane or helium-3).

Once the fluid source 106 provides the radioactive or isotope-labeledfluid to the chamber 102, the radioactive or isotope-labeled fluid maypermeate into the part. The amount of time that the part is exposed tothe radioactive or isotope-labeled fluid in the chamber may vary,depending on the desired configuration. In practice, the permeation ofthe radioactive or isotope-labeled fluid is related to the concentrationgradient of the radioactive or isotope-labeled gas, the location of thedefect, and the part's intrinsic permeability. The permeation of thefluid through the part could be modeled using Fick's laws of diffusion,and exposure times may be calculated accordingly. Deviations fromobedience to Fick's law may be an indication of the location of defectsin the part.

The fluid reclamation container 108 may be configured to remove theradioactive or isotope-labeled fluid from the chamber after thepermeation. By way of example, the fluid reclamation container 108 mayinclude a vacuum pump and cooler configured to reclaim the radioactiveor isotope-labeled fluid from the chamber 102 and a storage containerconfigured to store the radioactive or isotope-labeled fluid. The fluidreclamation container 108 may take other forms as well.

In some instances, the radioactive or isotope-labeled fluid may berecycled for use in subsequent testing. For example, the fluidreclamation container 108 may collect the radioactive or isotope-labeledfluid, and during a subsequent test, the fluid source 106 may providethe collected radioactive or isotope-labeled to the chamber 102 via thepathways 120 and 124. In other instances, the radioactive orisotope-labeled fluid reclaimed by the reclamation container 108 may bediscarded and might not be reused.

The detector 110 may be configured to detect a presence or absence ofradioactivity or isotope-labeled fluid in the part. By way of example,if the part was exposed to a radioactive fluid, the detector may beconfigured to detect a presence or absence of radioactivity entrained inthe part. On the other hand, if the part was exposed to anisotope-labeled fluid, the detector may be configured to detect apresence or absence of the isotope-labeled fluid entrained in the part.The detector may be an x-ray detector (e.g., a digital x-ray detector ora Geiger counter).

The detector may be connected to the chamber and configured to detectthe presence or absence of radioactivity or the isotope-labeled fluidentrained in the part after removal of the radioactive orisotope-labeled fluid from the chamber. The detector may be separatefrom the chamber (not shown) and configured to detect the presence orabsence of the radioactivity or isotope-labeled fluid entrained in thepart after removal of the part from the chamber

The controller 112 may be configured to control one or more of thevacuum source 104, fluid source 106, fluid reclamation container 108,detector 110, and indicator 114 in order to carry out testing of a partin accordance with the methods described herein. By way of example, thecontroller 112 may be configured to send instructions to the vacuumsource 104 causing the vacuum source to create a partial vacuum in thechamber 102. The controller may also be configured to send instructionsto the fluid source 106 causing the fluid source 106 to provide aradioactive or isotope-labeled fluid to the chamber 102. Additionally,the controller may be configured to send instructions to the fluidreclamation container 108 causing the fluid reclamation container 108 toreclaim the radioactive or isotope-labeled fluid from the chamber 102.The controller 112 may also be configured to send instructions to thedetector 110 causing the detector to detect a presence or absence ofradioactivity or isotope-labeled fluid entrained in the part.

One or more of the vacuum source 104, fluid source 106, fluidreclamation container 108, and detector 110 may be controlled manually(e.g., by an operator) without being controlled by the controller 112.Alternatively, the controller 112 and the indicator 114 may be omittedfrom the system 100 altogether (not shown).

In some examples, the controller 112 may be configured to receive datafrom the detector 110 indicating a presence or absence of radioactivityor isotope-labeled fluid, and send instructions to the indicator 114causing the indicator 114 to provide an indication of the presence orabsence of the radioactivity or isotope-labeled fluid in the part.

The indicator 114 may function to provide an output that is indicativeof the presence or absence of radioactivity or isotope-labeled fluid ina part. As such, the indicator 114 may comprise a light source (e.g., alight emitting diode) that is configured to provide a green or redlight, depending on whether the radioactivity or isotope-labeled fluidis present. Alternatively, the indicator 114 may comprise anelectroacoustic transducer (e.g., a speaker) that is configured toprovide an audible noise or alarm when radioactivity or isotope-labeledfluid is present. The indicator 114 may take other forms as well. Theindicator 114 may be an integrated component of the controller 112.

FIG. 2 is a schematic diagram of an example controller 200. Thecontroller 200 in FIG. 2 may represent the controller 112 (see FIG. 1).The controller 200 may be or include a computer, mobile device, orsimilar device that may be configured to perform the functions describedherein.

As shown in FIG. 2, the controller 200 may include one or moreprocessors 202, a memory 204, a communication interface 206, a display208, and one or more input devices 210. Components illustrated in FIG. 2may be linked together by a system bus, network, or other connectionmechanism 212. The controller 200 may also include hardware to enablecommunication within the controller 200 and between the controller 200and one or more other devices, such as any of the components of thesystem 100 (see FIG. 1). The hardware may include transmitters,receivers, and antennas, for example.

The one or more processors 202 may be any type of processor, such as amicroprocessor, digital signal processor, multicore processor, etc.,coupled to the memory 204. The memory 204 may be any type of memory,such as volatile memory like random access memory (RAM), dynamic randomaccess memory (DRAM), static random access memory (SRAM), ornon-volatile memory like read-only memory (ROM), flash memory, magneticor optical disks, or compact-disc read-only memory (CD-ROM), among otherdevices used to store data or programs on a temporary or permanentbasis.

Additionally, the memory 204 may be configured to store programinstructions 214. The program instructions 214 may be executable by theone or more processors 202. For instance, the program instructions 214may be executable to cause a vacuum source to reduce a pressure in achamber, cause a fluid source connected to the chamber to provide aradioactive or isotope-labeled fluid to the chamber, cause a fluidreclamation container to remove the radioactive or isotope-labeled fluidfrom the chamber, and/or cause a detector to detect a presence orabsence of radioactivity or isotope-labeled fluid in a part. The programinstructions 214 may also be executable to cause the one or moreprocessors 202 to perform other functions, such as any of the functionsdescribed herein.

The communication interface 206 may be configured to facilitatecommunication with one or more other devices, in accordance with one ormore wired or wireless communication protocols. For example, thecommunication interface 206 may be configured to facilitate wirelessdata communication for the controller 200 according to one or morewireless communication standards, such as one or more IEEE 802.11standards, ZigBee standards, Bluetooth standards, etc. As anotherexample, the communication interface 206 may be configured to facilitatewired data communication with one or more other devices.

The display 208 may be any type of display component configured todisplay data. As one example, the display 208 may include a touchscreendisplay. As another example, the display may include a flat-paneldisplay, such as a liquid-crystal display (LCD) or a light-emittingdiode (LED) display.

The one or more input devices 210 may include one or more pieces ofhardware equipment used to provide data and control signals to thecontroller 200. For instance, the one or more input devices 210 mayinclude a mouse or pointing device, a keyboard or keypad, a microphone,a touchpad, or a touchscreen, among other possible types of inputdevices.

FIG. 3 is a flowchart of an example method for testing a part. Method300 shown in FIG. 3 presents a method that, for example, could be usedwith the system 100 (see FIG. 1), or any of the systems disclosedherein. Example devices or systems may be used or configured to performlogical functions presented in FIG. 3. In some instances, components ofthe devices and/or systems may be configured to perform the functionssuch that the components are actually configured and structured (withhardware and/or software) to enable such performance. In other examples,components of the devices and/or systems may be arranged to be adaptedto, capable of, or suited for performing the functions. Method 300 mayinclude one or more operations, functions, or actions as illustrated byone or more of blocks 302-310. Although these blocks are illustrated ina sequential order, these blocks may also be performed in parallel,and/or in a different order than those described herein. Also, thevarious blocks may be combined into fewer blocks, divided intoadditional blocks, and/or removed based upon the desired implementation.

It should be understood that for this and other processes and methodsdisclosed herein, flowcharts show functionality and operation of onepossible implementation of present disclosure. In this regard, eachblock may represent a module, a segment, or a portion of program code,which includes one or more instructions executable by a processor forimplementing specific logical functions or steps in the process. Theprogram code may be stored on any type of computer readable medium ordata storage, for example, such as a storage device including a disk orhard drive. The computer readable medium may include non-transitorycomputer readable medium or memory, for example, such as computerreadable media that stores data for short periods of time like registermemory, processor cache, and RAM. The computer readable media may alsobe any other volatile or non-volatile storage systems. The computerreadable medium may be considered a tangible computer readable storagemedium, for example.

In addition, each block in FIG. 3 may represent circuitry that is wiredto perform the specific logical functions in the process. Alternativeimplementations are included within the scope of the examples of thepresent disclosure in which functions may be executed out of order fromthat shown or discussed, including substantially concurrent or inreverse order, depending on the functionality involved.

Initially, at block 302, the method 300 includes exposing a part to avacuum. In line with the discussion above, the part may be placed in achamber, and a vacuum source may create a partial vacuum in the chamber.The part may be exposed to a vacuum in an autoclave.

At block 304, the method 300 includes exposing the part to a radioactiveor isotope-labeled fluid under pressure. As discussed above, a fluidsource may provide the radioactive or isotope-labeled fluid to a chamberin which the part is located. The radioactive or isotope-labeled fluidmay be a gas or a liquid. Within the chamber, the radioactive orisotope-labeled fluid may then permeate into any cracks or voids withinthe part. The pressure within the voids or cracks may be less than thepressure within the chamber. Thus, the radioactive or isotope-labeledfluid may tend to permeate be retained in the voids or cracks.

At block 306, the method 300 includes reclaiming the radioactive orisotope-labeled fluid from the chamber. In line with the discussionabove, the radioactive or isotope-labeled fluid may be removed from thechamber and collected. Optionally, the radioactive or isotope-labeledfluid may be recycled and used again during subsequent testing.

At block 308, the method 300 includes detecting a presence or absence ofradioactivity or the isotope-labeled fluid entrained in the part. By wayof example, if the part was exposed to a radioactive fluid at block 304,then the detector may be configured to detect a presence or absence ofradioactivity entrained in the part. On the other hand, if the part wasexposed to an isotope-labeled fluid at block 304, then the detector maybe configured to detect a presence or absence of the isotope-labeledfluid entrained in the part. The detector may detect a concentration ofradioactivity or isotope-labeled fluid. For instance, a Geiger countermay determine the concentration. The detector or a separate controllermay then determine whether the concentration satisfies a predeterminedcriterion. For instance, the detector or controller may compare thedetected concentration to a threshold concentration.

In another example, a digital x-ray detector may generate an image ofthe part. If there is any radioactivity or isotope-labeled fluidentrained in the part, the radioactivity or isotope-labeled fluid may beobservable in the image. The digital x-ray detector may generate theimage without using an x-ray source. The digital x-ray detector or aseparate controller may then analyze the image to determine whether theimage is indicative of the presence of radioactive or isotope-labeledfluid in the part. Alternatively, a technician may review the image todetermine whether the image is indicative of the presence ofradioactivity or isotope-labeled fluid in the part.

At block 310, the method 300 includes providing an indication of thepresence or absence of the radioactivity or the isotope-labeled fluidentrained in the part. For example, if the detector is configured todetect a presence or absence of radioactivity, an indicator may providea green indication indicating the absence of radioactivity and that thepart does not appear to include any latent defects. Alternatively, theindicator may provide a red indication indicating the presence ofradioactivity and that the part appears to have a sub-surface latentdefect. Similarly, if the detector is configured to detect a presence orabsence of isotope-labeled fluid, an indicator may provide a greenindication indicating the absence of isotope-labeled fluid (e.g., lessthan a threshold detectable concentration), or provide an indicationindicating the presence of the isotope-labeled fluid.

In response to detecting the presence of radioactivity orisotope-labeled fluid, the method 300 may further include testing thepart using a secondary inspection technique. Examples of secondaryinspection techniques include x-ray detection, magnetic resonanceimaging (MRI), and computerized axial tomography (CAT) scanning, amongothers. The secondary inspection technique may be used to visualize anylatent defects within the part.

FIG. 4 is a flowchart of another example method for evaluating a surfaceof an object. Method 400 may include one or more operations, functions,or actions as illustrated by blocks 402-416 of the flowchart. Althoughthe blocks are illustrated in a sequential order, these blocks may alsobe performed in parallel, and/or in a different order than thosedescribed herein. Also, the various blocks may be combined into fewerblocks, divided into additional blocks, and/or removed from theflowchart, based upon the desired implementation of the method 400. Eachblock may represent a module, segment, or a portion of program code,which includes one or more instructions executable by a processor forimplementing specific logical functions or steps in the process. Inaddition, each block in FIG. 4 may represent circuitry that is wired toperform the specific logical functions in the process.

Initially, at block 402, the method 400 involves exposing a part to avacuum in a chamber. At block 404, the method 400 involves exposing thepart to a radioactive or isotope-labeled fluid in the chamber. At block406, the method 400 involves reclaiming the radioactive orisotope-labeled fluid from the chamber.

Further, at block 408, the method 400 involves detecting a presence orabsence of radioactivity or the isotope-labeled fluid entrained in thepart. If radioactivity or isotope-labeled fluid is present, then atblock 412, the method 400 involves providing a presence indication, and,at block 414, the method 400 involves testing the part using a secondaryinspection technique. Whereas, if radioactivity or isotope-labeled fluidis absent, then, at block 416, the method 400 involves providing anabsence indication, and an operator may then proceed to testing anotherpart.

The description of the different advantageous arrangements has beenpresented for purposes of illustration and description, and is notintended to be exhaustive or limited to the examples in the formdisclosed. After reviewing and understanding the foregoing disclosure,many modifications and variations will be apparent to those of ordinaryskill in the art. Further, different examples may provide differentadvantages as compared to other examples. The example or examplesselected are chosen and described in order to best explain theprinciples, the practical application, and to enable others of ordinaryskill in the art to understand the disclosure for various examples withvarious modifications as are suited to the particular use contemplated.

What is claimed is:
 1. A method for testing a part, comprising:exposing, in a chamber, a part having a permeable surface to aradioactive or isotope-labeled fluid under pressure to enable theradioactive or isotope-labeled fluid to permeate into a sub-surfacecrack or a sub-surface void defect internal to the part and becomeentrained within the sub-surface crack or the sub-surface void defectinternal to the part; and after exposing the part to the radioactive orisotope-labeled fluid under pressure, detecting a presence or absence ofradioactivity or the isotope-labeled fluid entrained within thesub-surface crack or the sub-surface void defect internal to the part todetect a presence or absence of a sub-surface latent defect of the part.2. The method of claim 1, wherein the part is a polymeric composite partcomprising multiple materials, and exposing the part to the radioactiveor isotope-labeled fluid under pressure comprises: enabling theradioactive or isotope-labeled fluid to permeate into the sub-surfacecrack or the sub-surface void defect between the multiple materials. 3.The method of claim 1, wherein the part comprises materials havingmultiple density or inhomogeneous constituents, and exposing the part tothe radioactive or isotope-labeled fluid under pressure comprises:enabling the radioactive or isotope-labeled fluid to permeate into thesub-surface crack or the sub-surface void defect of the multiple densityor inhomogeneous constituents.
 4. The method of claim 1, furthercomprising: exposing the part to the radioactive or isotope-labeledfluid under pressure by providing the radioactive or isotope-labeledfluid from a fluid source to the chamber.
 5. The method of claim 4,further comprising: reclaiming the radioactive or isotope-labeled fluidfrom the chamber and providing the radioactive or isotope-labeled fluidback to the fluid source via a pathway.
 6. The method of claim 1,further comprising: exposing the part to a vacuum before exposing thepart to the radioactive or isotope-labeled fluid under pressure.
 7. Themethod of claim 1, further comprising detecting the presence or absenceof radioactivity or the isotope-labeled fluid entrained within thesub-surface crack or the sub-surface void defect of the part using anx-ray detector.
 8. The method of claim 1, further comprising providingan indication of the presence or absence of radioactivity or theisotope-labeled fluid entrained within the sub-surface crack or thesub-surface void defect of the part.
 9. The method of claim 1, furthercomprising: based on detecting the presence of the radioactive orisotope labeled fluid entrained within the sub-surface crack or thesub-surface void defect of the part, inspecting the part using asecondary inspection technique.
 10. The method of claim 9, wherein thesecondary inspection technique includes one or more of magneticresonance imaging (MRI) and computerized axial tomography (CAT) scanningto visualize the sub-surface crack or the sub-surface void defect of thepart.
 11. The method of claim 1, further comprising: determining alocation of the sub-surface crack or the sub-surface void defect of thepart.
 12. A system for testing a part, comprising: a vacuum sourceconnected to a chamber configured to accept a part having a permeablesurface; a fluid source connected to the chamber and configured toprovide a radioactive or isotope-labeled fluid to the chamber to exposethe part to the radioactive or isotope-labeled fluid under pressure andenable the radioactive or isotope-labeled fluid to permeate into asub-surface crack or a sub-surface void defect internal to the part andbecome entrained within the sub-surface crack or the sub-surface voiddefect internal to the part; and a detector configured to detect apresence or absence of radioactivity or the isotope-labeled fluidentrained within the sub-surface crack or the sub-surface void defectinternal to the part to detect a presence or absence of a sub-surfacelatent defect of the part.
 13. The system of claim 12, furthercomprising: a fluid reclamation container connected to the chamber andto the fluid source, the fluid reclamation container configured toremove the radioactive or isotope-labeled fluid from the chamber andprovide the removed radioactive or isotope-labeled fluid back to thefluid source via a pathway.
 14. The system of claim 12, wherein thedetector is connected to the chamber and configured to detect thepresence or absence of radioactivity or the isotope-labeled fluidentrained within the sub-surface crack or the sub-surface void defect ofthe part after removal of the radioactive or isotope-labeled fluid fromthe chamber.
 15. The system of claim 12, wherein the detector isconnected to the chamber.
 16. The system of claim 12, wherein thedetector comprises an x-ray detector.
 17. The system of claim 16,wherein the x-ray detector comprises a Geiger counter.
 18. The system ofclaim 12, further comprising: an indicator configured to provide anindication of the presence or absence of radioactivity or theisotope-labeled fluid entrained within the sub-surface crack or thesub-surface void defect of the part.
 19. A controller comprising: aprocessor; and a computer-readable medium having stored thereininstructions that are executable to cause the controller to performfunctions comprising: causing a vacuum source to reduce a pressure in achamber, wherein a part having a permeable surface is located in thechamber, causing a fluid source connected to the chamber to provide aradioactive or isotope-labeled fluid to the chamber to enable theradioactive or isotope-labeled fluid to permeate into a sub-surfacecrack or a sub-surface void defect internal to the part and becomeentrained within the sub-surface crack or the sub-surface void defectinternal to the part, and causing a detector to detect a presence orabsence of radioactivity or isotope-labeled fluid entrained within thesub-surface crack or the sub-surface void defect internal to the part todetect a presence or absence of a sub-surface latent defect of the part.20. The controller of claim 19, wherein the functions furthercomprising: causing an indicator to provide an indication of thepresence or absence of radioactivity or isotope-labeled fluid entrainedwithin the sub-surface crack or the sub-surface void defect of the part.